This invention relates to an apparatus for positioning a magnetic head at a reference position, which is used in a magnetic tape apparatus for an image file information retrieval system or the like.
Recently, image information filing systems have been developed for rationalizing the filing of documents in offices. In the image information filing system, image information such as a great deal of documents produced in the office is optically read out and recorded on an endless magnetic tape having a number of information tracks in a magnetic tape apparatus, and the recorded image information is retrieved to read out desired image information so that user may have access to the information in a visible form. In the magnetic tape apparatus for such a system, a desired information track is selected by moving the magnetic head in the width direction of the magnetic tape using a stepper motor.
In such a magnetic tape apparatus, it is required that no deviation of the magnetic head from the position corresponding to each information track on the magnetic tape would result. To meet this requirement, the magnetic head has to be moved with respect to a position corresponding to a predetermined information track, i.e., reference track, on the magnetic tape. In a prior art apparatus, a microswitch or sensitive switch for detecting the magnetic head is provided at a position corresponding to the reference track on the magnetic tape. When a power is first applied to the apparatus, the magnetic head is previously moved, and upon actuation of the microswitch, i.e., upon arrival of the head to a position corresponding to the reference track, the head is detected to be at the reference position thereof. With the prior art apparatus, however, it is likely that the head fails to accurately correspond to the reference track at the time of the actuation of the microswitch due to variations in the operation thereof. Therefore, it is difficult to obtain an accurate reference position of the head.